Method and apparatus for spraying electrostatic dry powder

ABSTRACT

Dry nonconductive powder passes from a hopper by means of a vibrating plate through an adjustable, nonclogging eductor and is directed by means of a current of air issuing through a rectangular orifice from a variable volume plenum chamber into a venturi. The powder particles pass into the entrance of the venturi in a stream of air having a rectangular flow pattern or cross section and from the venturi through a discharge nozzle and from the discharge nozzle onto a substrate to be coated. Corona wires are located in the proximity of the issuing end of the discharge nozzle so as to charge the powder particles in order to direct them onto a substrate. A positive draft is maintained downstream from the venturi entrance and serves to pick up excess powder particles which are pneumatically conveyed back to the feed hopper.

United States Patent [72] lm entor John P. Dunn Elmira, NY. [21] Appl.No. 772,320 [22 Filed Oct. 31. 1968 [45] Patented Jan. 26, 1971 [73]Assignee F.1.N.D.1nc. Elmira, N.Y. a corporation of New York [54] METHODAND APPARATUS FOR SPRAYING ELECTROSTATIC DRY POWDER 19 Claims, 10Drawing Figs.

[52] US. Cl 239/3, 239/124:117/93.4 [51] Int. Cl B05b 5/02 [50] FieldofSearch 239/3,15. 379, 124; 222/193, 318;51/8. l l; l18/30831 l,(Church),93.4;117/17 [561 References Cited UNITED STATES PATENTS3,000,752 9/1961 Jackson et a1. 117/17 2,900,138 8/1959 Strate 239/85(X)Primary ExuminerLloyd L. King Assistant Examiner fiene A. ChurchAltarneySughrue, Rot-l well, Mion, Zinn and Macpeak ABSTRACT: Drynonconductive powder passes from a hopper by means of a vibrating platethrough an adjustable, nonclogging eductor and is directed by means of acurrent of air issuing through a rectangular orifice from a variablevolume plenum chamber into a venturi. The powder particles pass into theentrance of the venturi in a stream of air having a rectangular flowpattern or cross section and from the venturi through a discharge nozzleand from the discharge nozzle onto a substrate to be coated. Coronawires are located in the proximity of the issuing end of the dischargenozzle so as to charge the powder particles in order to direct them ontoa substrate. A positive draft is maintained downstream from the venturientrance and serves to pick up excess powder particles which arepneumatically conveyed back to the feed hopper.

PATENIEDJMBIQY: 3558.052

SHEET 2 OF 2 Hes INVENTOR JOHN PAUL DUNN ATTORNEYS METHOD AND APPARATUSFOR SPRAYING ELECTROSTATIC DRY POWDER BACKGROUND OF THE INVENTION 1.Field of the Invention The present invention relates broadly to thefield of spraying dry nonconductive powders onto various substrates forcoating purposes and, more particularly, to an apparatus whichpneumatically conveys the powder particles in a patterned flow through adischarge nozzle, into an area were the powder particles are charged andfinally directed onto the surface of a substrate to be coated.

2. Prior Art The broad concept of directing dry particles of powder orlike material onto a substrate through the .use of a directed flow ofair or like conveying fluid is generally well-known in the art. However,in the practice of these prior art methods and associated devicesdirected to the electrostatic spraying of dry nonconductive powders,difliculties are often encountered in attempting to apply coating ofuniform thickness and density. It is generally recognized thatuniformity of the deposited coating of powder can best be accomplishedif the spray consists of discrete and evenly dispersed particles,flowing through and from the discharge nozzle at a uniform rate.

Prior art systems encounter problems of uniform coating in that theresultant spray is a mixture of discrete and agglomerated particles Anumber of limitations on the existing spray systems are caused directlyby the high specific gravity of the powder or like materials beingsprayed. A powder having a high specific gravity has a tendency tosettle and collect or buildup within the apparatus of the spray system.This, of course, tends to clog the discharge nozzles and other deliveryconduits through which the powders are being pneumatically conveyed. Toovercome this settling problem, prior art-spraying systems have utilizedhigh velocity fluid flow for conveying the powder particles. This, inturn, has created a number of additional problems which also leads to anonuniform coating of the particles onto the desired substrate. Toovercome this settling problem, the velocities of the conveying air orfluid, and consequently, the velocities of the conveyed powderparticles, are normally greater than 600 feet per minute and often reacha velocity in excess of 1000 feet per minute. The flow of air and powderat this velocity through the discharge nozzles of the spraying devices,while eliminating the problem of settling within the nozzles, createdturbulence and resulted in the particles striking the desired substratewith such force as to bounce off or ricochet from the surface of thesubstrate thereby creating an uneven coating. Consequently, the existingspray systems are limited to spraying powders having a specific densityin a somewhat limited range because spraying powders having a relativelyhigh specific density necessitates the need of a high velocity air flowresulting in the above-mentioned problems.

SUMMARY OF THE INVENTION This invention relates to a spray system forspraying dry nonconductive powder particles uniformly onto varioussubstrates. The apparatus of the invention includes a feed bincontaining dry powder particles which is delivered into the air streamof an eductor system. The powder cascades, in the shape of asubstantially uniform ribbon of powder, downwardly through the eductorsystem to a point where it is picked up by an airjet issuing from avariable volume plenum chamber through a rectangular orifice. The airjet directs the powder particles into the entrance of arectangular-shaped venturi where the particles are evenly dispersedthrough the action of the air jet and the pressure differential createdby the venturi. The powder continues to flow through a rectangularshapedissuing nozzle and the particles are eventually charged by corona orlike conducting wires arranged in the proximity of the issuing end ofthe nozzle. The charge particles are then attracted to the oppositelycharged substrate to provide an even coating on the surface of thesubstrate.

The quantity of powder delivered to the surface of the sub strate isproportional to the rate of powder feed into the eductor system. to thevelocity of the air or other conveying fluid and to the volume ofconveying fluid which is a function of the plenum chamber orifice.Consequently, in the present invention. the necessity for a highvelocity gas flow is eliminated through the use of a gas plenum orificehaving a rectangularshape and by delivering a uniform curtain or ribbonof powder to the entrance to the venturi section.

The purpose of combining a system using a ribbon of powder and a powderdelivery system having a rectangular cross section is to overcome theproblems encountered when converting a flow of powder having a circularcross section into a flow powder having a rectangular flow pattern orcross section. When converting a circular flow pattern to a rectangularflow pattern, a larger pressure differential occurs causing a particlevelocity differential across the section or pattern of the flow. Thisresults in a nonuniform flow and also in a nonuniform deposition of thepowder onto the substrate. The present invention minimizes this pressuredifferential and creates an even laminar flow of powder by forming thedesired crosssectional pattern in the flow of powder at the entrance tothe venturi and accordingly designing the nozzle section following theventuri so as to maintain the laminar flow.

If the powder delivered to the venturi has a circular crosssectionalpattern, then the flow of powder traveling in the marginal portions ofthe circular cross section are traveling at a slower velocity than theflow of powder traveling in the central portion of the circular crosssection. If the powder traveling through the system has a sufficientlyhigh specific gravity, the slower velocity powder has a tendency tosettle which results in clogging of the system as previously mentioned.Consequently, to prevent settling, the velocity of the powder in theslower traveling portions of the circular pattern flow is increasedresulting in a proportional increase of the powder in the centralportion of the circular pattern. This greatly increased powder velocitycreates the problem of bounding or ricocheting of the particles from thesubstrate as previously described. When a relatively uniform rectangularcross section of powder is delivered to the venturi the powder in allportions of the cross-sectional pattern are traveling at approximatelythe same rate, consequently, the conveying gas may be allowed to travelat a relatively lower velocity without the worry of clogging of thesystem due to the settling of powders having a high specific gravity.While it is recognized that when spraying powders having a relativelyhigh specific gravity, the velocity of the conveying gas will have to beincreased, the present invention eliminates the need of a relativelyhigh velocity gas which results in the problems previously described.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 s a side elevation view of thespray system with a partial sectional view of the eductor and deliveryportions of the apparatus;

FIG. 2 is a top plan view of the nozzle and corona wire support means;

FIG. 3 is a cross-sectional view taken on line 3-3 of FIG. I through theplenum chamber viewing the plenum chamber orifice;

FIG. 4 is an enlarged top longitudinal sectional view taken on line 4-4of fig. l of the plenum chamber, plenum chamber orifice and venturiportion;

FIG. 5 is a side sectional view of a delivery nozzle arranged to coat asubstrate passing the discharge end of the nozzle in a horizontal plane;

FIG. 6 is a top plan view of FIG. 5;

FIGS. 7 and 8 are perspective views of two embodiments of a corona wireor like electrode structure which may be used with the presentinvention;

FIG. 9 is a perspective view of yet another embodiment of a corona wirearranged in the proximity of the discharge end of the nozzle, and

FIG. is a side elevational partially schematic view of a pluralityofdischarge nozzles operated from a central eductor.

DESCRIPTION OF PREFERRED EMBODIMENTS The apparatus of the presentinvention comprises a feed hopper I0 arranged above a vibrating pan I2which is activated into vibrating movement by a vibrating source [4.FIG. 1. The vibrating pan I2 communicates directly with the upperportion of eductor I6. The width of the eductor can be ad justed to varyin proportion to the size of the substrate and accordingly the quantityof powder to be ejected. The eductor communicates and leads past orificeplate 34 in which is located rectangular orifice 32. During operating, ajet of air is directed from variable volume chamber 24 through rectangular orifice 32 into the entrance of venturi 36. The rectangular orifice32 and the entrance 35 of the venturi 36 are axially aligned and arelocated on opposite sides of the eductor 16. The variable volume plenumchamber 24 includes an air inlet conduit 26 channeling air into thevariable volume chamber 24 from a source which is not shown. The conduit26 is supported within the housing 22 by a support member 28 and ismaintained in proper position by set screw 30.

FIG. 4 is an enlarged view of the plenum chamber and orifice plate 34.The orifice plate 34 is removably mounted within the spray housing so asto be able to change the size of the orifice opening 32. The adjustablemounting means include various notches 36 formed by a plurality of ribs38 arranged on each of the internal walls of housing 22. Altemately tothe embodiment shown in FIG. 4, the air plenum chamber itself may bemovably mounted within the spray housing by mechanically securingtogether plates 28 and 34 which define the chamber 24 so that they maybe movably mounted as a unit but immovable relative to one another. Inother words, plate 28 could be mechanically connected to orifice plate 3that longitudinal sliding movement of plate 28 would result in themovement of plate 34 either towards or away from the falling ribbon ofpowder 18. The effect of the relative position of plate 34 to the ribbonof falling powder 18 will be described in greater detail later.

The eductor 16 has a lower portion 17 in which a positive draft iscreated through an air flow entering through conduit 19 and check valve21 from a source which is not shown. A second venturi 23 is connected bycoupling 37 to the lower portion 17 of the eductor. A current of air isdirected into the entrance of venturi 23 through conduit 27 from asource which is not shown. Coupled to the exiting orifice 31 is a funnelor conical-shaped member 39 and a powder return conduit 29. The returnconduit 29 extends from the second venturi to the feed hopper l0 andserves to deliver by recirculation the excess powder particles whichwere not taken into the entrance 35 of the first venturi 36. The feedhopper has a vent such as a screen top 41 so that pressure of thedelivery stream can be relieved.

As previously mentioned, the entrance 35 of the venturi 36 is arrangedin axial alignment and on opposite sides of eductor 16. A dischargenozzle 38 having a rectangular cross section has a connection 40 to thediverging outlet 43 of the venturi 36.

Corona wires or like conducting wires 42 are mounted on a forklikestructure 4 in close proximity and behind the outlet 46 of nozzle 38.The forklike mounting structure 44 of corona wire 42 is itself supportedby arm member 48 which is adjustably attached by pivotal mount 50secured to the housing of the venturi by braces 52, or like mountingmeans, and which may be manually adjusted by knob 54 FIGS. 5 and 6 showan additional embodiment of the present invention comprising anothershaped nozzle 55 attached to venturi 36. The nozzle 55 of thisembodiment also has a rectangular cross section and is positioned tocoat a substrate passing the exit 58 of the nozzle in a horizontaldirection. Consequently, the longitudinal sides of orifice 58 arearranged in a vertical plan rather than in a horizontal plane as shownin FIGS. I and 2. It should be noted that entrance 57 to nozzle 55, aswell as any other nozzle useable with the device ofthe presentinvention. has the same configuration as nozzle 38 of FIGS. l and 2, soas to allow rapid removal and insertion of dilierent nozzles when achange in nozzles is desired.

FIGS. 8 and 9 are directed to different embodiments of a corona or likeconductor used to create the ionization field between the outlet of thedischarge nozzle and the substrate. FIG. 8 shows a plurality ofelectrodes 60 arranged on a crossbar support 62 which is attached to asupporting arm 64 in a manner similar to that previously described inthe embodiments shown in FIGS. I and 2. FIG. 9 is an embodiment ofthepresent invention which includes the arrangement of corona wires 66 in arectangular-shape in the proximity of but behind the exit 46 ofdischarge nozzle 38. The wires 66 are supported in a generallyrectangular-shape by means of support arms 68 which may or may not beattached to the housing of the spray device. The designations ALindicated in FIGS. 8 and 9 represent the length of the corona wires ordistances between the electrodes which may be varied in order to effectthe spray pattern issuing from the orifice 46 of the nozzle. as will bemore fully explained later.

FIG. [0 discloses another embodiment ofthe present invention whichincludes a plurality of nozzles 70, 72 and 74 directing powder or likematerial onto a vertically traveling substrate 76. Each of the nozzlesis associated with a separate variable volume plenum chamber and venturigenerally indicated at 76, 78 and 80, and operate in the same manner asthe embodiment shown in FIG. I. All of the nozzles, however, can operatefrom acommon feed hopper 84 and common eductor arrangement 82 and areserviced by a common return system generally indicated at 86.

The operation of the preferred embodiment shown in FIG. I will now bedescribed and will substantially the same as the operation of the systemutilizing the various embodiments shown in FIGS. 5 through I0.

The powder particles are delivered by means of gravity from feed hopper10 into the fibrating screen or tray 12. The dry powder particles aredelivered into the upper portion of eductor I6 in a substantiallyuniform curtain or ribbon I8. The uniform ribbon of powder then passesinto the air jet issuing from variable volume plenum chamber 24 throughrectangular orifice 32. As explained previously, the position of orificeplate 34 may be varied relative to the position of the falling ribbon ofpowder 18 and the entrance 35 to the venturi. By ad justing the distancebetween the orifice plate 34 and the ribbon of falling powder, theposition of the intersection between the air stream issuing from orifice32 and the powder curtain is changed. Accordingly, the point ofintersection between the issuing stream of air and the powder curtaindetermines the air flow pattern entering the venturi entrance 35.Consequently, a regulation of the powder transfer and the powderdispersion is established by changing the intersection between thedirected flow of air and the falling curtain of powder.

For example, considering that the position of the falling curtain ofpowder is relatively fixed in relation to the air chamber orifice 32 andthe venturi entrance 35 and further assuming that the cross-sectionalarea of the falling curtain of powder is generally constant, then byadjusting the air chamber orifice plate 34 closer to or away from thepowder curtain, the ratio of powder sprayed into the entrance to theventuri in relation to the amount returned through the return portion ofthe eductor 17 can be regulated. It is obvious that the current of airissuing from orifice 32 starts to diverge immediately upon clearingorifice 32. Consequently, it is apparent that the farther away orificeplate 34 is from the falling curtain of powder, the larger the air flowpattern of the issuing air current will be when it intersects thefalling curtain of powder. This results in a larger patter and increasedcased amount of particles traveling in the air flow beyond the point ofintersection.

A flow of particles having the desired cross-sectional flow pattern thenenters the venturi 36 where separation of the particles occurs. Theprinciple of using a converge-diverge member or venturi section is tocause particle separation by virtue of the air velocity differential andthe shear force established by the venturi. The particles then flow intothe entrance of nozzle 38 which also has a rectangular cross section asdescribed above. the dry nonconductive powder particles issue fromorifice 46 of nozzle 38 where they may be charged due to the action onthe particles by a corona wire 42 or like conductive wire.

The charging electrodes have been made adjustable and interchangeable tocontrol the patterns of the flow of particles as they issue from theexit 46 and are deposited onto the surface of a substrate (not shown).By changing the dimensions and/or position of the charging electrode,the electric field distribution established between the electrode andthe substrate is also changed, resulting in the ability to establishvarious spray patterns which may adequately serve to coat difficultyshaped parts or substrates. lt is also important to note that thecharging electrodes 42 are arranged behind the nozzle orifice in orderto prevent powders from adhering to the fine wires. Dust or powdersaccumulating on these electrodes reduce their operating efficiency whicheventually results in wire breakdown and a nonuniform coating. ln thespecific embodiment shown in FIG. 1, the arms 48 are connected directlyto a pivoted mount 50 which may be manually adjusted by means of knob54. Consequently, the conducting wires 42 are allowed to move in an arewhich, as previously mentioned. varies the pattern of the issuing powderparticles. The pattern of the issuing particles may also be varied bychanging the length AL (FIGS. 8 and 9) of the conductor wires therebychanging the ionization field between the issuing orifice 46 of thenozzle and the substrate.

Only a portion of those particles cascading from vibrating screen 12into the upper portion of eductor 16 are picked up by the air jetissuing from orifice 32. The excess particles fall through the lowerportion 17 of the eductor and, if necessary, their travel may be aidedby a positive draft by an air flow-entering portion 17 through an inletconduit 19. The air is provided from a source which is not shown and maybe controlled by check valve 21. Due to the positive draft, the excessparticles fall into a second venturi 23 into which a stream of air isdirected from a source not shown through inlet conduit 27. The particlesare directed into return conduit 29 through which they are conveyed backto the feed hopper for reuse. Although air has been mentioned as thecarrier gas, it will be apparent that other gases, preferably inert tothe powder and substrate, could be used. Further, the invention can, ifdesired, be utilized without the corona discharge wires.

lclaim:

l. A dry powder spray apparatus comprising;

a. a spray housing including a venturi with a powder-gas entrance;

b. a gas inlet for admitting gas under pressure to the housing, a gasinlet chamber directly communicating with the gas inlet and locatedahead of the venturi, the gas from said inlet directed toward theventuri through the gas inlet chamber;

c. a powder inlet to the spray housing above the inlet chamber,positioned such that the powder falling by gravity from the powder inletis picked up by the gas flowing from the gas inlet into the venturi, and

. an excess powder exit from the spray housing below the powder inletand the gas inlet chamber so that the excess powder which has not beenpicked up by the entering gas may flow from the housing.

2. Apparatus as in claim I further comprising a nozzle attached to theventuri exit.

3. Apparatus as in claim 2 wherein the nozzle is interchangeable withother nozzles having different crosssectional outlet openings and thesame inlet openings cooperating with the venturi exit end.

4. Spray apparatus as in claim 1 wherein the venturi is rectangular incross section and the venturi entrance is rectangular in section.

5. Apparatus as in claim 1 wherein one wall of the gas inlet chamber hasan orifice therein through which gas is directed into the venturientrance, the wall being adjustable to vary the gas flow pattern of thegas entering the venturi entrance.

6. A spray apparatus as in claim 5 wherein the adjustable wall ismovable relative to the venturi entrance.

7. A spray apparatus as in claim 1 wherein one wall of the gas inletchamber has an orifice therein through which gas is directed into theventuri entrance, the gas inlet chamber movably mounted within the sprayhousing, whereby said wall is adjustably positioned relative to thefalling powder so as to vary the pattern of gas entering the venturientrance.

8. A spray apparatus as in claim I further comprising a return eductorconnected to the excess powder exit for returning excess powder to apowder feed means.

9. A spray apparatus as in claim 8 further comprising: a gas inlet inthe excess powder exit prior to the return system whereby said inletcreates a positive draft serving to guide the excess powder into hereturn eductor system.

10. A spray apparatus as in claim I wherein the powder feed meansincludes a powder hopper. a vibratory screen, and a conduit connected tothe powder inlet.

11. An apparatus as in claim 1 wherein particle charging conductors aremounted adjacent the powder exit but upstream from the powder exit.

12. An apparatus as in claim 9 wherein said conducting wires are mountedso as to completely surround the powder exit.

13. An apparatus as defined in claim 12 wherein said conductors arearranged in a rectangular configuration.

14. A spray apparatus as defined in claim 13 wherein the conductors areadjustably attached to the outside of the spray housing.

IS. A spray apparatus as defined in claim 14 wherein a conductor issupported by an arm pivotally mounted on the spray housing so as to becapable of positioning said conductor in one of a number of positionsalong an arcuate path in the proximity of the powder exit.

l6. An apparatus as in claim I wherein there are a number of sprayhousings connected in series with a single feed hopper and a commoneductor system.

17. A method for the electrostatic spraying of dry particles onto asubstrate, said method comprising:

a. feeding by gravity a uniform ribbon of powder particles past adirected gas flow; V

b. forming a directed gas flow having a specifically and uniformlyshaped cross section;

c. directing said gas flow onto the flow of particles travelingtransversely to said directed gas flow;

d. directing a portion of said powder particles carried by said gas flowand said gas flow into a venturi;

e. conveying powder particles not carried by the gas flow into theventuri to recycle the powder particled;

f. separating the powder particles in the venturi from each otherthrough the action of the venturi;

g. guiding the particles into an electrical charging zone adjacent theventuri outlet, and

h. charging said particles and directing them onto a substrate.

18. A method of spraying particles as described in claim 17 furthercomprising forming said gas flow so as to have a rectangular crosssection whereby said flow of particles in the venturi has a rectangularcross section.

19. Apparatus as in claim 1, wherein the gas flow for carrying powder isless than 600 feet per second.

2. Apparatus as in claim 1 further comprising a nozzle attached to theventuri exit.
 3. Apparatus as in claim 2 wherein the nozzle isinterchangeable with other nozzles having different cross-sectionaloutlet openings and the same inlet openings cooperating with the venturiexit end.
 4. Spray apparatus as in claim 1 wherein the venturi isrectangular in cross section and the venturi entrance is rectangular insection.
 5. Apparatus as in claim 1 wherein one wall of the gas inletchamber has an orifice therein through which gas is directed into theventuri entrance, the wall being adjustable to vary the gas flow patternof the gas entering the venturi entrance.
 6. A spray apparatus as inclaim 5 wherein the adjustable wall is movable relative to the venturientrance.
 7. A spray apparatus as in claim 1 wherein one wall of the gasinlet chamber has an orifice therein through which gas is directed intothe venturi entrance, the gas inlet chamber movably mounted within thespray housing, whereby said wall is adjustably positioned relative tothe falling powder so as to vary the pattern of gas entering the venturientrance.
 8. A spray apparatus as in claim 1 further comprising a returneductor connected to the excess powder exit for returning excess powderto a powder feed means.
 9. A spray apparatus as in claim 8 furthercomprising: a gas inlet in the excess powder exit prior to the returnsystem whereby said inlet creates a positive draft serving to guide theexcess powder into he return eductor system.
 10. A spray apparatus as inclaim 1 wherein the powder feed means includes a powder hopper, avibratory screen, and a conduit connected to the powder inlet.
 11. Anapparatus as in claim 1 wherein particle charging conductors are mountedadjacent the powder exit but upstream from the powder exit.
 12. Anapparatus as in claim 9 wherein said conducting wires are mounted so asto completely surround the powder exit.
 13. An apparatus as defined inclaim 12 wherein said conductors are arranged in a rectangularconfiguration.
 14. A spray apparatus as defined in claim 13 wherein theconductors are adjustably attached to the outside of the spray housing.15. A spray apparatus as defined in claim 14 wherein a conductor issupported by an arm pivotally mounted on the spray housing so as to becApable of positioning said conductor in one of a number of positionsalong an arcuate path in the proximity of the powder exit.
 16. Anapparatus as in claim 1 wherein there are a number of spray housingsconnected in series with a single feed hopper and a common eductorsystem.
 17. A method for the electrostatic spraying of dry particlesonto a substrate, said method comprising: a. feeding by gravity auniform ribbon of powder particles past a directed gas flow; b. forminga directed gas flow having a specifically and uniformly shaped crosssection; c. directing said gas flow onto the flow of particles travelingtransversely to said directed gas flow; d. directing a portion of saidpowder particles carried by said gas flow and said gas flow into aventuri; e. conveying powder particles not carried by the gas flow intothe venturi to recycle the powder particled; f. separating the powderparticles in the venturi from each other through the action of theventuri; g. guiding the particles into an electrical charging zoneadjacent the venturi outlet, and h. charging said particles anddirecting them onto a substrate.
 18. A method of spraying particles asdescribed in claim 17 further comprising forming said gas flow so as tohave a rectangular cross section whereby said flow of particles in theventuri has a rectangular cross section.
 19. Apparatus as in claim 1,wherein the gas flow for carrying powder is less than 600 feet persecond.